Antibiotics: Nucleic acid inhibitors Flashcards
what are nucleic acid inhibitors?
they are inhibitors of folic acid
they are direct inhibitors of nucleic acid synthesis
what are the 2 categories of nucleic acid inhibitors?
- Inhibitors of folic acid synthesis
- Direct inhibitors of nucleic acid synthesis
what 2 enzymes are used by bacteria in order to make its DNA strands?
DNA topoisomerase II (gyrase)
DNA topoisomerase IV
what vitamin is essential for bacteria to synthetize nucleic acid?
TH4
(tetrahydrofolic acid)
do bacteria synthesize their own folate?
yes
what is the active form of folate made by bacteria?
TH4
what enzyme do bacteria need to make their own folate?
dyhydrofolate reductase to make dihydrofolate - the precursor of folate
what do you use to inhibit dihydrofolate reductase?
what will this cause?
folate antagonist or trimetroprim
prevents conversion of dihydrofolate to tetrahydrofolate
what is an example of a folic acid inhibitor?
sulfonamides
how do sulfonamides work?
compete with PABA, therefore inhibiting folate synthesis
what are 2 examples of sulfonamides?
sulfamethaxazole
silver sulfadiazine
when are sulfonamides administered?
mild urinary tract infections
conjunctivitis
burns
what are sulfonamides known as?
antimetabolites
what adverse reactions can sulfonamides cause?
- hypersensitivity = steven johnson syndrome (peeling skin/blisters, fever, respiratory problems)
- nephrotoxicity = crystal formation (white urine)
- hemolysis: glucose 6 phosphate dehydrogenase deficiency
- kernicterus = displacement of bilirubin
what is cotrimoxazole used to treat?
PCP (pneumocystis jirovecii)
urinary tract infection
what is cotrimoxazole ?
combination of sulfamethoxazole (SXT) & trimethoprim (TMP)
sulfamethoxazole (SXT) & trimethoprim (TMP) in combination will act as bacteriostatic or bacteriocidal?
they will act as bacteriocidal
what are Fluoroquinolones?
drugs that inhibit bacterial enzymes needed for DNA replication
what enzymes do Fluoroquinolones target?
DNA topoisomerase II (DNA gyrase)
DNA topoisomerase IV
how many groups do Fluoroquinolones have?
3
what is norfloxacin used for?
what other drug can be used?
urinary tract infection
cipro
what is the 1st group of fluoroquinolones?
norfloxacin
what is the 2nd group of fluoroquinolones?
Ciprofloxacin**, Ofloxacin
what is the 3rd group of fluoroquinolones?
Sparfloxacin
2nd group fluoroquinolones is used against what bacteria?
gram -
3rd group fluoroquinolones is used against what bacteria?
gram - and +
what drug is used to treat Typhoid fever?
ciproflaxin
what drug is used to treat Uncomplicated Urinary tract infection?
cotrimoxazole
what drug is used to treat complicated Urinary tract infection?
Ciprofloxacin
what is complicated UTI?
when infection reaches kidneys
what is uncomplicated UTI?
when infection is in the urethra
what adverse effects can occur while taking fluoroquinones?
They deposit in cartilage and cause ruptured tendons*
fluoroquinones should not be given to whom?
pregnant women and children
what type of bacteria does Metronidazole (Flagyl)** target?
is it bacteriostatic or bacteriocidal?
anaerobic bacteria and some parasites
bacteriocidal
how does metronidazole work?
Forms free radical toxic metabolites in bacterial cell
what is an adverse reaction to metronidazole?
disulfiram like reaction (vomiting, nausea, tachycardia)
Sulfonamides will inhibit what bacterial enzyme needed for folate synthesis?
Dihydropteroate syhthase
